The present invention relates to exposure to an image of a photographic film, and particularly relates to an image exposure apparatus and an image exposure method in which a photosensitive material is exposed to add any photographic effects to an image of a photographic film. For example, as the photographic effects, the contrast of an image is corrected or controlled, and photographic paper is exposed to the corrected or controlled image light. Further there is a photographic effect in which a photosensitive material is exposed to a combination of an image of a photographic film and another image.
Recently, when image exposure is conducted in a photographic printer, it is often to expose photographic paper to a combination of an image light of a negative film and another image light such as a frame, a graphic, or characters.
In the prior art, this exposure is conducted while inserting a pattern mask such as a lith film into an optical path, writing image information which is to be combined, to photographic paper by a laser, or inserting a liquid crystal mask into an optical path.
Such exposure has problems as follows: In exposure using a pattern mask, the pattern mask must be inserted in the vicinity of photographic paper. As a result, the operations of inserting and detaching the pattern mask must be conducted in a dark room.
In exposure using a laser, due to scanning exposure a considerably long exposure time is required and the structure of movable parts for conducting the scanning is complicated.
In exposure using a liquid crystal mask, pixels constituting the liquid crystal mask are arranged in a matrix. Particularly when exposure to a curved image is conducted, therefore, there arises a problem in that the resulting image fails to form smooth lines and has low definition.
Alternately, the contrast characteristic afore-said of an image recorded on a photographic film depends on the conditions at thus recording. Black-and-white photographic paper or color photographic paper is exposed to the image light having the contrast.
With respect to black-and-white photographic paper, a wide variety of kinds which have different tones ranging from high contrast to low contrast are available. When a black-and-white image is to be printed, photographic paper having a tone which is suitable for the contrast of an image of a photographic film or the intention of the photographer is selected.
With respect to color photographic paper, unlike black-and-white photographic paper, a wide variety of kinds which have different tones are not available, and only one kind having a certain tone is available. When a color image is to be printed, therefore, a contrast conversion is performed so that an image of a photographic film is expressed under the density latitude which can be expressed by the color photographic paper, thereby obtaining a printed image of low or high contrast.
When an image of a photographic film is to be printed while its tone is changed to a lower level, exposure is conducted while inserting a mask in which the brightness pattern is the inversion of that of the negative image, into an optical path. In contrast, when the image of the photographic film is to be printed while its tone is changed to a higher level, exposure is conducted while inserting a mask in which the brightness pattern is the same as that of the negative image, into the optical path.
In an example of a known contrast correction method which does not use such a mask, a liquid crystal panel where electrodes are arranged in a matrix form is used, and the transmittance of each pixel is controlled so as to obtain a desired amount of light. According to this method, the contrast of an image which is to be printed can be corrected by controlling the voltage applied to the electrodes.
When an image is to be printed to black-and-white photographic paper, as described above, various kinds of photographic paper having different tones may be available. However, photographic paper of a desired tone is not always available.
When an image is to be printed to color photographic paper, considerable time and labor are required to determine an appropriate mask and insert the mask into an optical path, thereby requiring a great amount of skill.
In the case where an image is to be printed to color photographic paper with using the above-mentioned liquid crystal panel in place of a mask, the voltage to be applied must be controlled for every region. A configuration of the circuit is complicated.
In a color image exposure apparatus of the level which is usually obtainable in the market, therefore, it is difficult to attain a simple exposing process in which the contrast of an image is corrected.